Power operated hydraulic actuator



Oct. 4, 1955 E. J. RINGER 2,719,405

POWER OPERATED HYDRAULIC ACTUATOR ori inal; Filed Dec. 22, 1945 2Sheets-Sheet l I TOR. 5 05 LIE/v65? tg MSW ATTORNEY @ct. 4, 1955 E. J.RINGER 2,719,405

POWER OPERATED HYDRAULIC ACTUATOR Original Filed D80. 22, 1945 2Sheets-Sheet 2 I N V EN TOR. 1405 J A M/ EE A T TOR/VB Y United StatesPatent tion Corporation, South Bend, Ind., a corporation of DelawareOriginal application December 22, 1945, Serial No. 636,582, new PatentNo. 2,617,261, dated November 11, 1952. Divided and this applicationJune 16, 1952, Serial No. 293,795

4 Claims. (Cl. 60--54.6)

This invention relates to power operated hydraulic actuators andparticularly to the construction of a combined differential air pressurepower unit and hydraulic cylinder operated thereby, such as disclosed inPrice Patent No. 2,353,755, which issued July 18, 1944. This case is adivision of my application Serial No. 636,582, filed December 22, 1945,now Patent No. 2,617,261.

The primary object of the present invention is to improve and simplifythe construction of such a combination power unit and hydraulicactuator, to the end of reducing the expense of building the same,particularly by making it easier to machine the bore of the hydraulicactuator, and by reducing the amount of waste or scrap material.

A further object of the present invention is to simplify the assemblingof the combined power unit and hydraulic actuator.

Other objects and advantages will become apparent during the course ofthe following description, reference being had therein to theaccompanying drawings, in which:

Figure l is a vertical section taken through a combined power unit andhydraulic actuator embodying my invention, the remaining elements of anillustrative pressure transmitting system being shown diagrammatically;and

Figure 2 is a vertical section taken through a second embodiment of myinvention.

Referring to Figure l, the structure with which I am primarily concernedis the combination of the differential air pressure power cylinderindicated generally at 12 and the hydraulic actuator indicated generallyat 14, said hydraulic actuator being operable by the power unit 12. Thecomplete system, which may be used to control the application of brakesor the like, includes a conventional master cylinder 16, a plurality ofconven tional Wheel cylinders 18, a conduit 20 connecting mastercylinder 16 to a port 22 provided in the combination power and hydraulicunit, and conduits 24 connecting the Wheel cylinders to a port 26 alsoprovided in the combination power and hydraulic unit.

Pressure developed in the manually operated master cylinder 16 acts onpiston 28 to develop a force acting through rod 30 on piston 32, whichis reciprocable in the bore 34 of hydraulic actuator 14. The pressuredeveloped in the master cylinder 16 also acts against avalve-operating-piston 36 which is connected to avalve-seat-providingmember 38. A valve member 40 is adapted to cooperatewith valve seat 38 to control the opening 42 provided in the center ofsaid valve seat. In the released position of the system, valve member 40is spaced from its seat and aperture 42 therefor permits communicationbetween chamber 44 and chamber 46. Because chamber 46 is connected bymeans of conduit 48 with a suitable source of vacuum, such as the usualintake manifold, while chamber 44 is connected by means of conduit 50with chamber 52 of the power cylinder, which in turn is connected bypassage 53 with chamber 54 of the power cylinder, the rear surfaces oftandem pistons (or pressure responsive movable members) 56 and 58 arenormally subjected to vacuum. Chambers 60 and 62, which are in front ofthe respective pistons 56 and 58, are connected by means of conduit 64to the vacuum source. Therefore, when the valve members 38 and 40 are inthe relative positions shown, vacuum is present on both sides of bothpower pistons and spring 66 holds the tandem piston combination in theleftward position, as shown, the power pistons being interconnected bymeans of the tube 68. A sealed partition 70 prevents communicationbetween chambers 54 and 60 of the power cylinder.

When the pressure acting against piston 36, tending to move the sametoward the left, is sufficient to compress spring 72, valve seat 38contacts valve element 40, thereby cutting off communication between thevacuum source, on the one hand, and chambers 52 and 54 of the powercylinder, on the other hand. Further movement of piston 36 towards theleft lifts valve members 74 and 76 from their respective seats, therebypermitting air to flow from chamber 78 into chamber 44 and thence tochambers 52 and 54 of the power cylinder, developing a differential overthe power cylinder pistons to move the same toward the right. The forceexerted by the power cylinder pistons through rod 30 urges piston 32 inhydraulic actuator 14 on its pressure stroke, the total output of thehydraulic actuator being developed by the combined effort of the powercylinder pistons and of the manually created pressure acting againstpiston 28.

A fast application valve corresponding to that disclosed in T. H. Thomasapplication Serial No. 623,832, filed October 22, 1945, now abandoned,may be used to speed the change of pressure in power cylinder chamber54. This valve includes poppet 61 and diaphragm 63 connected thereto.The chamber at the right of the diaphragm is connected by means ofconduit 65 with chamber 44 of the control valve, and the chamber at theleft of the diaphragm is connected by means of passage 67 with chamber54 of the power cylinder. Operation of the fast application valve isfully explained in the Thomas application above referred to.

In the released position of piston 32, communication is permittedbetween the bore 34 of actuator 14 and the hydraulic reservoir 80, fluidbeing allowed to flow past ball check valve 82, and through passage 84to the rear of piston 32, whence it communicates through opening 86 withthe reservoir. During the pressure stroke of the power pistons 56 and58, the ball valve 82 cuts off the passage 84 because of the removal ofpressure exerted on forked member 88 by washer 90, which in releasedposition causes the forward extension 92 of said forked member to holdthe ball valve away from its seat.

The present invention is primarily concerned with the construction ofthe front or right end of power cylinder 12 and the hydraulic actuator14 which is supported thereon. In general, power cylinder 12 comprises acylindrical shell 94, to which is secured by suitable means, such as aplurality of bolts 96, an end plate 98. In the illustrated powercylinder, because it is designed to use a tandem piston construction, asecond shell is provided, separated from the shell 94 by theaforementioned partition 70. At the rear of shell 100 a suitable endplate 102 is provided, which supports the structure of the controlvalve.

The shells 94 and 1% may be conveniently formed by a deep drawingprocess wherein the wall portion is gradually forced outwardly until thecylindrical shape is assumed. End plate 102, partition 70, and end plate98 are all formed by casting, because of the relatively intricate shapeof these parts.

The casting 98 which provides the front end plate of the power cylinderhas formed integral therewith the reservoir casing 99. Also integralwith the end plate 98 is an outwardly extending hollow boss 104 which isinternally threaded as shown at 106. Screwedinto boss 104 is a tubularmember 108 which may be simply a piece of conventional tubing providedwith suitable externally threaded portions, and internally machined toobtain the proper wall finish for the hydraulic bore 34.

The inner end 110 of tube 108 is suitably guided in casting 98, and theopening 86 is formed in the wall of the tube.

The power piston 58 is connected by means of the crosspin 112 to the rod30, the front end of said rod being connected by means of a cross-pin114 with the piston 32. The rod 30 extends through an opening 116provided in a closure member or plug 118 which is inserted in an opening120 provided through the center of casting 98. Suitable seals 122 and124 and a gasket 125 are provided to prevent communication betweenchamber 62 of the power cylinder and chamber 126 at the rear of thehydraulic actuator.

The tube 108, after it has been screwed into the threaded openingprovided in boss 104, is secured in position by means of a lock nut 128.A suitable seal 130 is required to prevent escape of liquid from thereservoir 80 along the outer surface of the tube 108, and the usual seal132 is provided to prevent communication between chamber 134 of thehydraulic actuator and chamber 126 thereof, except through passage 84 inpiston 32.

Secured to the forward end of tube 108, as by the illustrated threadedconnection, is a fitting 136, which contains the port 26, into which theend of conduit 24 may be inserted, the fitting 136 also containing ableed opening 138 normally closed by plug 140.

The combination of a power cylinder end plate having an integral bosswith a tubular member secured in said boss and machined to form acylinder bore has certain important advantages over power operatedhydraulic actuators heretofore used: (1) the walls of tube 108 are lesslikely to have objectionable porosity than the walls of a cast cylinder;(2) the tubular member 108 is easier to handle during machining of thehydraulic bore than a casting would be; and (3) if, for any reason, thebore of the hydraulic actuator proves to be unfit, only the tube need bescrapped and the rest of the parts are not affected. The significance ofthe listedadvantages is due to the fact that the critical part of acombination unit of this type is the bore in which the hydraulic pistonoperates. The requirements as to the other parts of the structure arenot so critical and do not require such careful handling and inspection.

An additional advantage of the present invention lies in the ease withwhich the structure may be assembled. Heretofore it'would have beenextremely difficult to assemblea hydraulic piston having a directmechanical connection with the operating rod, such as that provided bypin. 114. Such a direct mechanical connection between the power pistonand the hydraulic piston is advantageous because the power cylinderreturn spring retracts the hydraulic piston, and there is no need for anadditional return spring in the hydraulic actuator. With the presentconstruction, after the power cylinder has been assembled, and the endplate 98 secured thereto, the power piston assembly may be drawn towardthe right byapplying suitable pressure thereto, thus causing the end ofrod 30 to protrude beyond the casting 98. It is relatively simple toconnect piston 32 to the protruding end of rod 30by means of pin 114,and then slide tube 108 over piston 32 and screw the tube into positionin member 98.

Figure 2 illustrates the application of the principles of my inventionto a smaller unit having a single-piston power cylinder. In thisconstruction, the power cylinder may consist primarily of a cup-shapedstamped shell 142 which contains a power piston (or pressure responsivemovable wall) 144, and to the front end of which is se cured a casting146. The casting 146 is provided With a forwardly extending hollow boss148 which is in- .ternally threaded as .shown at 150 to receive theexternally threaded tubular member 152. Rod 154 is provided with athreaded portion 156 and may thus be clamped by means of nut 158 topower piston 144. At its forward end rod 154 is secured by means of pin159 to piston 160., which is reciprocable in the bore 162 provided intubular member 152.

Because port 164 is connected directly to the operator operatedmastercylinder, there is no need for a reservoir inthis construction.Port 164 is connected through chamber 166 and passage 168 with thechamber 170, in which is located valve operating piston 172. Chamber 174of the power cylinder is in constant communication with the vacuumsource through a suitable port (not shown), and, in released position ofthe unit, chamber 178 of the power cylinder is also connected to thevacuum source through conduit 180 and port 182 of the valve. Movement ofpiston 172 under the influence of pressure developed in the operatoroperated master cylinder first cuts off chamber 178 from the vacuumsource and subsequently brings it into communication with the air whichenters through chambers 1.84, thereby causing the power piston to traveltoward the right and move piston 169 on the pressure stroke. Themanually developed pressure present in chamber 166 acts against the rearof piston 16.0 to assist the power piston in developing brake ap y ngeff rt.

As in the embodiment shown in Figure 1, a suitable fitting 186 issecured to tube 152 at the outer end thereof, a lock nut 188 is used tosecure tube 152 in position, and a suitable plug or closure member 190is used to close the centrally located opening in end plate 146, exceptfor the hole 192 through which the rod 154 extends.

It will be apparent that the casting 146 not only provides an end platefor the power cylinder and a hollow boss to receive the tubular member152, but also furnishes partof the casing of the control valve, thecasting 194 being secured thereto to complete the valve housing. Inorder to provide a bore for valve operating piston 172, a sleeve 196 maybe secured in place in casting 14 6 as shown.

Although particular embodiments of my invention have been described, itwill be understood by those skilled in t the art that the object of theinvention may be attained by the useof constructions different incertain respects from those disclosed without departing from theunderlying principles of the invention. I therefore desire by thefollowing claims to include within the scope of my invention all suchvariations and modifications by which substantially the results of myinvention may be obtained through the useof substantially the same orequivalent means.

I claim:

1. A combined differential air pressure power unit and hydraulicactuator operated thereby comprising a cylindrical shell for said powerunit, a power piston reciprocable in said shell, an end plate secured toone end of said shell having an opening-through the center thereof, anda reservoir cavity formed therein and having an integral hollowinternallythreaded boss concentric with said opening and extending otwardly from the end plate, an externally threadedtubular member securedin said hollow boss and providing a hydraulic master cylinder bore, saidtube being apertured to communicate with the interior of the reservoir,a piston reciprocable in said bore, means including a. rod and across-pin at each end thereof connecting the last-named piston to thepower piston, a closure member closing the centrally locatedopeningthrough the end plate except for a hole which accommodates theaforementioned rod, a lock-nut screwed onto said tubular member andresting against the outer end of the hollow boss to retain the tubularmember in position, and a fitting secured to the outer end of thetubular member and adapted to receive the end of a liquid-carryingconduit.

2. A combined differential air pressure power unit and hydraulicactuator operated thereby comprising a cylindrical shell for said powerunit, a pressure responsive movable wall reciprocable in said shell, anend plate with a reservoir cavity formed therein secured to one end ofsaid shell having an integral hollow internally threaded boss extendingoutwardly therefrom, an externally threaded tube secured in said bossand providing a hydraulic master cylinder bore, a piston slidablyreceived in said bore, means connecting said piston to theaforementioned pressure responsive movable wall, a lock-nut screwed ontosaid tubular member and resting against the adjacent end of the boss toretain the tubular member in position, and a fitting secured to theouter end of the tubular member and adapted to receive the end of aliquid-carrying conduit.

3. A combined difierential air pressure power unit and hydraulicactuator operated thereby comprising a cylindrical shell for said powerunit, a pressure responsive movable wall reciprocable in said shell, anend plate having an integral hollow internally threaded boss, areservoir formed within said end plate, an externally threaded tubesecured in said boss and providing a hydraulic master cylinder bore, apiston slidably received in said bore, a portion of said threaded tubebeing apertured to provide communication with said reservoir, meansconnecting said piston to the aforementioned pressure-responsive wall,and a lock-nut screwed into said tubular member and resting against thehollow end of the sleeve to retain the tubular member in position.

4. A combined differential air pressure power unit and hydraulicactuator operated thereby comprising a cy1indrical shell for said powerunit, a pressure responsive movable wall reciprocable in said shell, anend plate provided with a hollow boss, a reservoir carried by said endplate, a tube telescoped into said hollow boss to provide a hydraulicmaster cylinder bore, a piston slidably received in said bore, and meansconnecting said piston to said pressure-responsive movable wall.

References Cited in the file of this patent UNITED STATES PATENTS2,241,374 Alfieri May 13, 1941

